<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <title>Title</title>
  <style>
    .app {
      width: 0;
      height: 0;
      border-width: 8px;
      border-style: dashed dashed solid;
      border-color: transparent transparent #c2c2c2;
    }
  </style>
</head>

<body>
  <div class="app"></div>
</body>